Huh, that's a pickle. Assuming that as a vampire I'm one of the kind of hot Underworld-style vampires rather than the bestial 30 Days of Night vampires, that could be kinda fun. Though I would miss all the daylight things. I've been on night shift before for two whole years, so I've had a taste of a nocturnal existance. Though I'd have plenty of time to write, I wouldn't be able to garden, go to the Farmer's Market, or go shopping at most places. But alternatively there would be other vampires around to hang with, and I'd be super fast or strong or have really keen senses, depending on what version of vampire I was.
On the other hand, as a vampire hunter, I'd either be keeping the same hours as a vampire, or doing all my hunting during the day. Or both, really messing up my circadean rhythm. And while I'd have the job satisfaction of ridding the world of evil undead, I would also be putting my family and friends in jeopardy constantly. I mean, who wants the stress of having to not only fight against vampires but have to constantly worry that your loved ones are going to end up in the crossfire? That would not be cool.
In short, I think I'd be a vampire. Mostly because I'm kind of a lazy ass, and having to haul around weapons all the time would be exhausting.